Polishing wear has been known to occur on piston rings@ cylinder bores@ valve lifters@ hydraulic components@ rolling-element bearings and gear teeth. The bright@ polish surfaces may look good@ but polishing wear is detrimental because it is a high wear phenomenon which reduces the geometric accuracy of the components. A case history is presented of a gearbox which suffered extensive polishing wear of the gear teeth and rolling-element bearings. The results of research into the basic mechanism of polishing wear@ and laboratory analyses of materials and lubricants are presented. Polishing wear is shown to be due to fine-scale abrasion. It is promoted by a combination of a fine abrasive and a gear oil with chemically-active additives.